Steps to reproduce:
1. Download the attached user's project "Project.zip"
2. Make sure that the "XR Plug-in Management Settings" is not open (make sure before that OpenXR was not checked)
3. Click in the top menu bar on "BugReport/ToggleOpenXR"
4. Open the Plugin Management Settings -> Android Platform
5. Observe that the OpenXR Loader is enabled
6. Disable OpenXR Loader
7. Click in the top menu bar on "BugReport/ToggleOpenXR" with the XR Management settings window open
8. Observe that the OpenXR Loader does not become active

Expected Results: XRPackageMetadataStore.AssignLoader works regardless whether the XR package selection UI is open or not
Actual Results: XRPackageMetadataStore.AssignLoader doesn't work when the XR package selection UI is open

Reproducible with: XR Management 4.2.0 - 4.4.1 (2021.3.36f1, 2022.3.22f1, 2023.2.16f1, 6000.0.0b13)
Could not test below 4.2.0 due to package version not being available on supported streams

Testing Environment: Windows 11
Not reproducible on: No other environment tested

Notes:
-Issue is reproducible with other XR Loaders (OculusXR, ARCore, Unity Mock HMD)
-This is also reproducible via the `XRGeneralSettingsPerBuildTarget.XRGeneralSettingsForBuildTarget(this.BuildTargetGroup).AssignedSettings.TryAddLoader`